/*
 * Copyright (c) 2019, NVIDIA CORPORATION. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef TENSORRT_LOGGING_H
#define TENSORRT_LOGGING_H

#include "NvInferRuntimeCommon.h"
#include <cassert>
#include <ctime>
#include <iomanip>
#include <iostream>
#include <ostream>
#include <sstream>
#include <string>

using Severity = nvinfer1::ILogger::Severity;

class LogStreamConsumerBuffer : public std::stringbuf{
    public:
        LogStreamConsumerBuffer(std::ostream& stream, const std::string& prefix, bool shouldLog):mOutput(stream),mPrefix(prefix),mShouldLog(shouldLog){}

        LogStreamConsumerBuffer(LogStreamConsumerBuffer&& other):mOutput(other.mOutput){}

        ~LogStreamConsumerBuffer(){
            // std::streambuf::pbase() gives a pointer to the beginning of the buffered part of the output sequence
            // std::streambuf::pptr() gives a pointer to the current position of the output sequence
            // if the pointer to the beginning is not equal to the pointer to the current position,
            // call putOutput() to log the output to the stream
            if (pbase() != pptr()){
                putOutput();
            }
        }

        // synchronizes the stream buffer and returns 0 on success
        // synchronizing the stream buffer consists of inserting the buffer contents into the stream,
        // resetting the buffer and flushing the stream
        virtual int sync(){
            putOutput();
            return 0;
        }

        void putOutput(){
            if (mShouldLog){
                // prepend timestamp
                std::time_t timestamp = std::time(nullptr);
                tm* tm_local = std::localtime(&timestamp);
                std::cout << "[";
                std::cout << std::setw(2) << std::setfill('0') << 1 + tm_local->tm_mon << "/";
                std::cout << std::setw(2) << std::setfill('0') << tm_local->tm_mday << "/";
                std::cout << std::setw(4) << std::setfill('0') << 1900 + tm_local->tm_year << "-";
                std::cout << std::setw(2) << std::setfill('0') << tm_local->tm_hour << ":";
                std::cout << std::setw(2) << std::setfill('0') << tm_local->tm_min << ":";
                std::cout << std::setw(2) << std::setfill('0') << tm_local->tm_sec << "] ";
                // std::stringbuf::str() gets the string contents of the buffer
                // insert the buffer contents pre-appended by the appropriate prefix into the stream
                mOutput << mPrefix << str();
                // set the buffer to empty
                str("");
                // flush the stream
                mOutput.flush();
            }
        }

        void setShouldLog(bool shouldLog){
            mShouldLog = shouldLog;
        }

    private:
        std::ostream& mOutput;
        std::string mPrefix;
        bool mShouldLog;
};

//!
//! \class LogStreamConsumerBase
//! \brief Convenience object used to initialize LogStreamConsumerBuffer before std::ostream in LogStreamConsumer
//!
class LogStreamConsumerBase{
    public:
        LogStreamConsumerBase(std::ostream& stream, const std::string& prefix, bool shouldLog):mBuffer(stream, prefix, shouldLog){}

    protected:
        LogStreamConsumerBuffer mBuffer;
};

//!
//! \class LogStreamConsumer
//! \brief Convenience object used to facilitate use of C++ stream syntax when logging messages.
//!  Order of base classes is LogStreamConsumerBase and then std::ostream.
//!  This is because the LogStreamConsumerBase class is used to initialize the LogStreamConsumerBuffer member field
//!  in LogStreamConsumer and then the address of the buffer is passed to std::ostream.
//!  This is necessary to prevent the address of an uninitialized buffer from being passed to std::ostream.
//!  Please do not change the order of the parent classes.
//!
class LogStreamConsumer:protected LogStreamConsumerBase,public std::ostream{
    public:
        //! \brief Creates a LogStreamConsumer which logs messages with level severity.
        //!  Reportable severity determines if the messages are severe enough to be logged.
        LogStreamConsumer(Severity reportableSeverity, Severity severity):
            LogStreamConsumerBase(severityOstream(severity), severityPrefix(severity), severity <= reportableSeverity),
            std::ostream(&mBuffer),mShouldLog(severity <= reportableSeverity),mSeverity(severity){}

        LogStreamConsumer(LogStreamConsumer&& other):
            LogStreamConsumerBase(severityOstream(other.mSeverity), severityPrefix(other.mSeverity), other.mShouldLog),
            std::ostream(&mBuffer),mShouldLog(other.mShouldLog),mSeverity(other.mSeverity){}

        void setReportableSeverity(Severity reportableSeverity){
            mShouldLog = mSeverity <= reportableSeverity;
            mBuffer.setShouldLog(mShouldLog);
        }

    private:
        static std::ostream& severityOstream(Severity severity){
            return severity >= Severity::kINFO ? std::cout : std::cerr;
        }

        static std::string severityPrefix(Severity severity){
            switch (severity){
                case Severity::kINTERNAL_ERROR: return "[F] ";
                case Severity::kERROR: return "[E] ";
                case Severity::kWARNING: return "[W] ";
                case Severity::kINFO: return "[I] ";
                case Severity::kVERBOSE: return "[V] ";
                default: assert(0); return "";
            }
        }

        bool mShouldLog;
        Severity mSeverity;
};

//! \class Logger
//!
//! \brief Class which manages logging of TensorRT tools and samples
//!
//! \details This class provides a common interface for TensorRT tools and samples to log information to the console,
//! and supports logging two types of messages:
//!
//! - Debugging messages with an associated severity (info, warning, error, or internal error/fatal)
//! - Test pass/fail messages
//!
//! The advantage of having all samples use this class for logging as opposed to emitting directly to stdout/stderr is
//! that the logic for controlling the verbosity and formatting of sample output is centralized in one location.
//!
//! In the future, this class could be extended to support dumping test results to a file in some standard format
//! (for example, JUnit XML), and providing additional metadata (e.g. timing the duration of a test run).
//!
//! TODO: For backwards compatibility with existing samples, this class inherits directly from the nvinfer1::ILogger
//! interface, which is problematic since there isn't a clean separation between messages coming from the TensorRT
//! library and messages coming from the sample.
//!
//! In the future (once all samples are updated to use Logger::getTRTLogger() to access the ILogger) we can refactor the
//! class to eliminate the inheritance and instead make the nvinfer1::ILogger implementation a member of the Logger
//! object.

class Logger : public nvinfer1::ILogger{
    public:
        Logger(Severity severity = Severity::kWARNING):mReportableSeverity(severity){}

        //!
        //! \enum TestResult
        //! \brief Represents the state of a given test
        //!
        enum class TestResult{
            kRUNNING, //!< The test is running
            kPASSED,  //!< The test passed
            kFAILED,  //!< The test failed
            kWAIVED   //!< The test was waived
        };

        //!
        //! \brief Forward-compatible method for retrieving the nvinfer::ILogger associated with this Logger
        //! \return The nvinfer1::ILogger associated with this Logger
        //!
        //! TODO Once all samples are updated to use this method to register the logger with TensorRT,
        //! we can eliminate the inheritance of Logger from ILogger
        //!
        nvinfer1::ILogger& getTRTLogger(){
            return *this;
        }

        //!
        //! \brief Implementation of the nvinfer1::ILogger::log() virtual method
        //!
        //! Note samples should not be calling this function directly; it will eventually go away once we eliminate the
        //! inheritance from nvinfer1::ILogger
        //!
        void log(Severity severity, const char* msg) override{
            LogStreamConsumer(mReportableSeverity, severity) << "[TRT] " << std::string(msg) << std::endl;
        }

        //!
        //! \brief Method for controlling the verbosity of logging output
        //!
        //! \param severity The logger will only emit messages that have severity of this level or higher.
        //!
        void setReportableSeverity(Severity severity){
            mReportableSeverity = severity;
        }

        //!
        //! \brief Opaque handle that holds logging information for a particular test
        //!
        //! This object is an opaque handle to information used by the Logger to print test results.
        //! The sample must call Logger::defineTest() in order to obtain a TestAtom that can be used
        //! with Logger::reportTest{Start,End}().
        //!
        class TestAtom{
            public:
                TestAtom(TestAtom&&) = default;

            private:
                friend class Logger;

                TestAtom(bool started, const std::string& name, const std::string& cmdline):mStarted(started),mName(name),mCmdline(cmdline){}

                bool mStarted;
                std::string mName;
                std::string mCmdline;
        };

        //!
        //! \brief Define a test for logging
        //!
        //! \param[in] name The name of the test.  This should be a string starting with
        //!                  "TensorRT" and containing dot-separated strings containing
        //!                  the characters [A-Za-z0-9_].
        //!                  For example, "TensorRT.sample_googlenet"
        //! \param[in] cmdline The command line used to reproduce the test
        //
        //! \return a TestAtom that can be used in Logger::reportTest{Start,End}().
        //!
        static TestAtom defineTest(const std::string& name, const std::string& cmdline){
            return TestAtom(false, name, cmdline);
        }

        //!
        //! \brief A convenience overloaded version of defineTest() that accepts an array of command-line arguments
        //!        as input
        //!
        //! \param[in] name The name of the test
        //! \param[in] argc The number of command-line arguments
        //! \param[in] argv The array of command-line arguments (given as C strings)
        //!
        //! \return a TestAtom that can be used in Logger::reportTest{Start,End}().
        static TestAtom defineTest(const std::string& name, int argc, char const* const* argv){
            auto cmdline = genCmdlineString(argc, argv);
            return defineTest(name, cmdline);
        }

        //!
        //! \brief Report that a test has started.
        //!
        //! \pre reportTestStart() has not been called yet for the given testAtom
        //!
        //! \param[in] testAtom The handle to the test that has started
        //!
        static void reportTestStart(TestAtom& testAtom){
            reportTestResult(testAtom, TestResult::kRUNNING);
            assert(!testAtom.mStarted);
            testAtom.mStarted = true;
        }

        //!
        //! \brief Report that a test has ended.
        //!
        //! \pre reportTestStart() has been called for the given testAtom
        //!
        //! \param[in] testAtom The handle to the test that has ended
        //! \param[in] result The result of the test. Should be one of TestResult::kPASSED,
        //!                   TestResult::kFAILED, TestResult::kWAIVED
        //!
        static void reportTestEnd(const TestAtom& testAtom, TestResult result){
            assert(result != TestResult::kRUNNING);
            assert(testAtom.mStarted);
            reportTestResult(testAtom, result);
        }

        static int reportPass(const TestAtom& testAtom){
            reportTestEnd(testAtom, TestResult::kPASSED);
            return EXIT_SUCCESS;
        }

        static int reportFail(const TestAtom& testAtom){
            reportTestEnd(testAtom, TestResult::kFAILED);
            return EXIT_FAILURE;
        }

        static int reportWaive(const TestAtom& testAtom){
            reportTestEnd(testAtom, TestResult::kWAIVED);
            return EXIT_SUCCESS;
        }

        static int reportTest(const TestAtom& testAtom, bool pass){
            return pass ? reportPass(testAtom) : reportFail(testAtom);
        }

        Severity getReportableSeverity() const{
            return mReportableSeverity;
        }

    private:
        //!
        //! \brief returns an appropriate string for prefixing a log message with the given severity
        //!
        static const char* severityPrefix(Severity severity){
            switch (severity){
                case Severity::kINTERNAL_ERROR: return "[F] ";
                case Severity::kERROR: return "[E] ";
                case Severity::kWARNING: return "[W] ";
                case Severity::kINFO: return "[I] ";
                case Severity::kVERBOSE: return "[V] ";
                default: assert(0); return "";
            }
        }

        //!
        //! \brief returns an appropriate string for prefixing a test result message with the given result
        //!
        static const char* testResultString(TestResult result){
            switch (result){
                case TestResult::kRUNNING: return "RUNNING";
                case TestResult::kPASSED: return "PASSED";
                case TestResult::kFAILED: return "FAILED";
                case TestResult::kWAIVED: return "WAIVED";
                default: assert(0); return "";
            }
        }

        //!
        //! \brief returns an appropriate output stream (cout or cerr) to use with the given severity
        //!
        static std::ostream& severityOstream(Severity severity){
            return severity >= Severity::kINFO ? std::cout : std::cerr;
        }

        //!
        //! \brief method that implements logging test results
        //!
        static void reportTestResult(const TestAtom& testAtom, TestResult result){
            severityOstream(Severity::kINFO) << "&&&& " << testResultString(result) << " " << testAtom.mName << " # "
                                             << testAtom.mCmdline << std::endl;
        }

        //!
        //! \brief generate a command line string from the given (argc, argv) values
        //!
        static std::string genCmdlineString(int argc, char const* const* argv){
            std::stringstream ss;
            for (int i = 0; i < argc; i++){
                if (i > 0)
                    ss << " ";
                ss << argv[i];
            }
            return ss.str();
        }

        Severity mReportableSeverity;
};

namespace{
    //!
    //! \brief produces a LogStreamConsumer object that can be used to log messages of severity kVERBOSE
    //!
    //! Example usage:
    //!
    //!     LOG_VERBOSE(logger) << "hello world" << std::endl;
    //!
    inline LogStreamConsumer LOG_VERBOSE(const Logger& logger){
        return LogStreamConsumer(logger.getReportableSeverity(), Severity::kVERBOSE);
    }

    //!
    //! \brief produces a LogStreamConsumer object that can be used to log messages of severity kINFO
    //!
    //! Example usage:
    //!
    //!     LOG_INFO(logger) << "hello world" << std::endl;
    //!
    inline LogStreamConsumer LOG_INFO(const Logger& logger){
        return LogStreamConsumer(logger.getReportableSeverity(), Severity::kINFO);
    }

    //!
    //! \brief produces a LogStreamConsumer object that can be used to log messages of severity kWARNING
    //!
    //! Example usage:
    //!
    //!     LOG_WARN(logger) << "hello world" << std::endl;
    //!
    inline LogStreamConsumer LOG_WARN(const Logger& logger){
        return LogStreamConsumer(logger.getReportableSeverity(), Severity::kWARNING);
    }

    //!
    //! \brief produces a LogStreamConsumer object that can be used to log messages of severity kERROR
    //!
    //! Example usage:
    //!
    //!     LOG_ERROR(logger) << "hello world" << std::endl;
    //!
    inline LogStreamConsumer LOG_ERROR(const Logger& logger){
        return LogStreamConsumer(logger.getReportableSeverity(), Severity::kERROR);
    }

    //!
    //! \brief produces a LogStreamConsumer object that can be used to log messages of severity kINTERNAL_ERROR
    //         ("fatal" severity)
    //!
    //! Example usage:
    //!
    //!     LOG_FATAL(logger) << "hello world" << std::endl;
    //!
    inline LogStreamConsumer LOG_FATAL(const Logger& logger){
        return LogStreamConsumer(logger.getReportableSeverity(), Severity::kINTERNAL_ERROR);
    }

} // anonymous namespace

#endif // TENSORRT_LOGGING_H
